In general, pasta sheets for producing coverings for gyoza, shaomai, Chinese cakes, wonton, etc., are produced by adding water to wheat flour, kneading, extending and molding, and the main starting material is wheat flour regardless of the use.
While, in addition to wheat flour, cereal flour such as rice flour, corn flour, soybean flour, etc., as well as buckwheat flour, etc., and starch other than the cereal flour may also be used as a starting material for producing pasta sheets, wheat flour is special among these starting materials. When wheat flour is kneaded with water, the wheat protein forms gluten generating a unique glutinuousness and functions as a binding substance to enhance the pasta sheet strength. Since other cereal flours do not have these properties, wheat flour has hitherto been not only used for pasta but also essential as a binding substance for producing pasta where other cereal flours are also present.
Thus, in the conventional production of pasta sheets, wheat flour has been the main ingredient and the pasta sheet strength has been achieved by the presence of wheat gluten. On the other hand, in order to improve the softness of the pasta sheet and also to impart a transparent appearance to the sheet, a process for producing pasta sheets by adding raw starch to wheat flour is known.
However, where wheat flour and raw starch are used in combination, the degree of transparency of the pasta sheet produced is low, and, for example, in the case of gyoza, etc., it is difficult to obtain a commercial product having a see-through covering so that the color of the filling can be seen through the covering.
In order to enhance the degree of transparency of the pasta sheet, it is difficult to use a starting material mainly comprising starch, and transparent coverings which have hitherto been manually produced are made from wheat starch alone by adding hot water thereto, kneading, extending using a rolling pin, etc., and incorporating a filling.
As has been described hereinabove, in order to obtain pasta sheets having a high degree of transparency, it is important to produce them mainly from starch. However, the pasta sheet strength is inadequate where the pasta sheet is produced industrially by machine, and thus molding by machine is almost impossible.
Therefore, with the conventional process employing wheat flour and starch in combination and comprising adding water and kneading or the process also conventionally used and comprising adding hot water to wheat starch, kneading and molding the transparency of pasta sheets is poor, or even if transparency is obtained, the production thereof on an industrial scale is impossible from standpoints of mechanical strength, glutinuousness, etc., of pasta sheets.